Telegraphic apparatus



YB. THOMPSON & 0. SELDEN.

TELEGRAPHIG APPARATUS.

No. 253,957. Patented Feb-21,1882.

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UNITED STATES PATENT OFFIC BENJAMIN THOMPSON AND CHARLES SELDEN, OF TOLEDO, OHIO.

TELEGRAPHIC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 253,957, dated February '21, 1882.

Application filed November 21, 1879.

To all whom it may concern:

Be it known that we, BENJAMIN THOMPSON and CHARLES SELDEN, of Toledo, in the county of Lucas and State of Ohio, have invented Certain new and useful Improvements in Tele-' responding to the closing and opening of the transmitting-key have been produced by the closing and breaking of the primary circuit of the induction-coil. By this plan, however, the impulses corresponding to the opening and closing of the key are not of the same strength, since, as is well known, the induced or secondary current produced by the breaking of the primary current and demagnetization of the core is stronger than that which is set up when the primary circuit is closed and the core .is magnetized.

The object of our invention is to remedy this defect and to cause the secondary reversed currents corresponding to the opening and closing of the transmitting-keyto be of equal strength, thus producing a uniform and certain operation of the polarized relay in response to such reversals of current.

An additional object of our invention in this connection is to increase the strength of the reversed currents.

' The object of our inventionis also to improve the construction of the polarized relay at the receiving end of the line.

In carrying out our invention weuse as a transmitter a pole-chan gin g device instead of a circuit maker and breaker, and instead of making'and breaking the current from the 10- cal battery which passes through the primary coil we reverse the polarity of the local-battery current without, however, breaking its continuity. The effect of this is to increase very considerablythe extent and suddenness of the charge in the primary coil and thecore, and consequently to increase the strength of the induced currents. Moreover, since the change at each movement of the transmittingkey, whether up or down, is the sameviz., from a positive current of certain strength to a negative current of the same strength, and vice versa--the positive current from the secondary of the induction-coil is of the same strength as'the negative, and vice versa. The movements of the polarized relay' at the receivin g end of the line in both directions are thus made in obedience to currents of the same strength.

In Figure 1 of the drawings, F represents an ordinary pole-chan gin g key, whose contacts M, N, M, N, O, and P control, in the well-known manner, the circuit of a local battery, G,whose current flows in the one direction or the other through the primary coil I of an inductioncoiI,H, of any preferred construction, an earth or return wire, and the contact-points of the key F, according to the position of said key. This key is a continuity-preserving key, so that the reversals of the local-battery current are accomplished without absolutelyinterrupting the current. The pole-changing key is actuated in the ordinary manner by an electro-1nagnet,K ,which alternately attracts and releases the key as the local-circuit key is depressed and released, so as to make and break the circuit of the local battery K. Thus when key K is closed a current of one polarity, say, flows from battery G through the primary of the induction-coil. When said key is opened the positive current from battery G is immediately succeeded by a current of the opposite polarity, but of the same strength, thus producing in the secondary coil a secondary current of the same strength, but of the opposite polarity from that produced by the closing of the key.

L represents the secondary coil, wound upon a portion of a core, 0, of less diameter than that upon which the primary is wound. By thus constructing the core we find by actual trial ,that the efficiency of the coil is considerably increased, and that, other conditions bein g the same, secondary currents of greater strength are obtained than when the core is of uniform cross section. One end of the secondarycoil is connected to earth in the usual way, the other end being connected toline. In

the present instance we have shown it as connected to a differentially wound relay interposed between the line and the induction-coil, so that the outgoing induced currents do not actuate the relay at that end of the line, but do actuate the relay at the distant end. This arrangement is well knownin the art, and need not be described in all its details.

R H E 0 represent the adj ustable resistance, placed in the artificial line to earth.

8 represents the condenser, V the resistance, and R T the connecting wires, of the condenser arrangement for neutralizing static discharge, patented to us by reissued Letters Patent No. 8,889, July 8,1879.

The polarized receiver consists of a short straight bar electro-magnet, B, pivoted at the point E, and provided with a contact arm or bar, D, arranged to make and break the circuit of a local battery and reading-sounder in the well-known manner. Both poles of the electro-magnet are acted upon by permanent magnets a and a, of the horseshoe or equivalent form, the poles of each magnet embracing and acting upon one of the poles of the electromagnet B. The poles of the magnets are arranged in the manner indicated by the signs and so that the force tending to swing I the magnet B is made up of the attractive and repulsive actions existing between the four poles of two permanent magnets and thetwo poles of the electro-maguet. For-idstance, if

a current of the polarity proper to cause the right-hand end of the core to exhibit polarity and the left-hand end flow over the line, the electro-magnet will be caused to swing inthe direction of the hands ot'awatch and close the local circuit, its movement being produced by the concurrent action of all four poles of the permanent magnets, since in this case the repellent force due to thepole of a, the attractive force from its negative, and the simultaneous attractive and repulsive effects between the opposite pole of the electro-magnet and the poles of the permanent magnet will all assist one another. When the line-current is reversed the'local circuit is broken.

therelay itself may be readily used as a sounder.

ance of the balance of attractive effects, as in some polarized relays.

Adjusting-screws for adjustingthe permanent magnets with relation to the poles of the electro-magnet are indicated at O O.

Fig. 2 shows a construction of the adjusting No stops other than the poles of the permanent magnet are employed, as the poles of the clectro-magnet may be allowed to come in contact with thepermanent magnet without any difficulty from sticking, since the reversals of movement are produced by repulsive as well as attractive efiects, instead of by a disturbdevices that may be employed for adjusting the permanent magnets, the poles of the permanent magnets being here shown in end view. The permanent magnet rests upon a base-block, as indicated, and the adjustingscrew is mounted in standards in the ordinary way, and is seated in a groove in the upper face of the magnet, so as to prevent thelatter from shifting longitudinally. Flanges upon the spindle of the adjusting-screw engage with the sides of the magnet-poles, as shown, and serve to give the required lateral movement to the magnet for the purposes of adjustment.

The operation of our improved apparatus will be readily understood. Normally no current flows to line. Local battery G .flows through the primary of the induction-coil with acertain polarity, giving to thecore of the induction-coil a-magnetic polarity of, a certain sign. When key Kis depressed the flow of the local-battery current is reversed, andthe polarity existing in the core ,ot',the induction-coil not only ceases, but is instantly succeeded by a polarity of the opposite signs. The effect is to cause a secondary induced. current or impulse toflow to line, which is of the proper polarity to cause the electrornagne't B to turn and close thelocal circuit of the reading-sounder. The induced current is of, but momentary duration, but the relay remains in the, position assumed by reason of the attraction between its soft-iron cores and the poles ofthemagnet with which it. is in contact .or near which it rests. When the transmitting-key K is opened the local-battery current is reversed, assuming its normal polarity, the magnetism of the core (3 is instantly changed to the opposite sign, and an. induced electric current orimpulse of the opposite sign, but of thesame strength as that produced by the closing of the key K, is sent to line, and the relay is. thrown back to its first position.

We do not limit ourselves to any particular form or construction of the various elements of our invention, and we wish it to be understood that other forms' of induction-coiland other styles of continuity-preserving currentreversing apparatus may be used in place of that described, the object being, so far as the latterelement isconcerned, to reverse the direction of the currentchargingthe'primary coil without interrupting its continuity. Other devices or arrangements of apparatus besides what are technically known as ,pole-changing or reversing keysmay be fused forthis purpose.

It is obvious that so far as concernsthecombination of a polarized receiver and transmitting apparatus of the character above described any polarized receiver will answer the the purposes of the invention. What we claim as, our invention is- 1. The combination of a polarized receiver, an induction-coil whose secondary, is connected to line, and suitable means,substantially as described, for reversing the direction'ot the primary current of said induction-coil without interrupting the continuity of the current, as

and for the purpose set forth.

2. The combination, substantially as described, of an induction-coil whose secondary is connected to line, a primary coil in circuit with a local battery, and a continuity-preserving pole-changing key whose contact-points are in said local-battery circuit.

3. The combination of a swinging straightbar electro-magnet and two permanent horseshoe-magnets arranged each to embrace with BENJAMIN THOMPSON.

CHARLES SELDEN.

- Witnesses:

JNo. SHOWEL, GEORGE A. HEINL. 

